public class Likou_treehigh {
    class Solution {
        public int calculateDepth(TreeNode root) {
            if(root==null){
                return 0;
            }
            int t1 = calculateDepth(root.left);
            int t2 = calculateDepth(root.right);
            return t1>t2? t1+1 : t2+1;
        }
    }
}
